1. Field of the Invention
The present invention illustrates a high temperature protection system, and more particularly, the high temperature protection system for adjusting duty cycle by using a pulse width modulation signal.
2. Description of the Prior Art
With the advancement of techniques, various electrical devices with high operational performance are widely adopted. Nowadays, most electrical devices are required to perform high processing speed and low response time in conjunction with a high-level processor integrated to a micro volume circuit. Thus, the electrical devices can be operated by users at any time and in any place. For example, the specification of iPhone 5s states that an A7-typed processor is used. The specification of iPhone 6 Plus states that an A8-typed processor is used. Another example is that the central processing unit (CPU) of the personal computer is upgraded from Intel® Core™ i5 to Intel® Core™ i7. Specifically, power consumption and heat generation of the electrical device are increased since the clock frequency of the processor is increased. Thus, the performance of heat dissipation components such as heat dissipation fans, a water cooling system, thermally conductive adhesive, and a heat sink attracts more attention. Among these heat dissipation devices, a water cooling system has the best heat dissipation performance yet has a large circuit volume, high cost, and high noise. Thermally conductive adhesives and heat sinks have smaller volume with inferior heat dissipation performance since they only use a medium for conducting heat. As a result, heat dissipation fans become the most popular devices for dissipating heat in general electric devices.
Generally, when the electrical device is operated, a thermal detection module inside an integrated circuit of a fan system is enabled. When an abnormally high temperature is detected by the thermal detection module (i.e., the abnormally high temperature is occurred when the fan system is overloaded or heat dissipation between PN-junctions of the integrated circuit is failed), the thermal detection module controls the fan system to pause all operations. As a result, when the abnormally high temperature is detected, the fan system is paused directly, thereby leading severe damages of the device (i.e., CPU) which needs to dissipate heat since a function of heat dissipation is also paused.